The proposed studies will utilize a recently developed NH3-gas electrode for further elucidation of: (1) The relation of blood and CSF ammonia and glutamine levels, colonic gas and fecal ammonia levels and RBC ammonia levels to the degree of cerebral dysfunction in patients with hepatic encephalopathy, as related to non-ionic diffusion theory. The effects of current therapies will also be evaluated. (2) The release of artifactual ammonia from glutamine and from plasma, as related to glutamin and specific protein levels, and the release of ammonia from feces. (3) The role of pH and K plus gradients on the transmembrane distribution of ammonia, as related to non-ionic diffusion theory. Detailed studies are also proposed to further assess RBC ammonia production and to determine the feasibility of using the electrode for estimation of intracellular pH. (4) The mechanisms governing the intestinal absorption of ammonia, specifically as related to fecal ammonia and buffer content and to different models for non-ionic diffusion. Both in vitro and in vivo studies are outlined, the latter in dog as well as man.